In order to estimate the population indoor exposure, a national radon monitoring programme is presently being carried out by the Radiation Protection Centre of the Haut Commissariat a la Recherche of Algeria. In this survey passive time-integrating dosemeters of the 'open' type, based on nuclear track detection, were used. So far, about 201 randomly selected houses have been monitored in some regions of Algeria, including Algiers, Ain Defla, Ain-Oussera, Batna, Bou-Saada and Ghardaia. The means of the concentrations in these cities were found to be respectively 32, 47, 33, 26, 31 and 33 Bq.m-3, leading to average effective dose equivalents of 0.98, 1.44, 1.01, 0.81, 0.96 and 0.95 mSv per year, respectively. The results obtained are presented and discussed.